Re: PATCH: Unix98 pty support.

Jakub Jelinek (
Wed, 21 Jan 1998 17:39:29 +0100 (MET)

> > Attached is the latest version of my pty patch for linux kernel
> > 2.1.{78,79,80}.
> ...
> > No additional functionality is needed to implement Unix98 ptys in
> > the linux kernel. Work is progressing on integrating this support into
> > glibc. The device number {5,2} has been allocated by the linux device
> > list maintainer for /dev/ptmx.
> A reservation on usage of "/dev/ptmx" named object...
> I recall having heard Alan Cox to say NAY on this before on
> basis of this easily breaking iBCS -- Running SCO binaries
> on top of iBCS detects /dev/ptmx NAME, and then the libc stuff
> statically linked into those binaries ASSUMES existence of
> STREAMS in the system. (Need I continue ? Naeh, ask Alan..)

I think the solution for this is that SCO emulated binaries will have
different root, in which it will have it's own devices. We have such a code
already for solaris, sunos and irix in the kernel. All those files reside
in /usr/gnemul/platform/

The problem with the current scheme is that this mostly works,
but e.g. getcwd may have problems with it, if you do cwd in a tree outside
of /usr/gnemul/xx/. The right solution, I think, is an overlay file system,
configurable as much as possible and Linux kernel which just unconditionaly
chroots foreign emulated programs into their emulation roots. That way, they
can see most parts of your normal tree, but with some files/directories
overrided, hidden or added. Anyone looking for a useful Linux project?

Jakub Jelinek | |
Administrator of SunSITE Czech Republic, MFF, Charles University
Ultralinux - first 64bit OS to take full power of the UltraSparc
Linux version 2.0.32 on a sparc machine (291.64 BogoMips).